In chemically amplified photoresist compositions, an acid is generated from an acid generating agent upon irradiation with an exposure light such as an ArF excimer laser beam and a KrF excimer laser beam at a light-exposed site, and a reaction catalyzed by the acid allows the difference in dissolution rates in a developer solution to be produced between the light-exposed site and a light-unexposed site, thereby enabling a resist pattern to be formed on a substrate.
Along with miniaturization in processing techniques, such photoresist compositions are required not only to exhibit a superior resolving ability, but also to be superior in a line width roughness (LWR) performance, which is indicative of a variation in the line width of a resist pattern. To address the demand, incorporation of an acid diffusion control agent into the photoresist compositions is employed for the purpose of properly controlling the diffusion of the acid generated from the acid generating agent. In order to improve various performances of the photoresist compositions, various acid diffusion control agents having a specific structure have been investigated (see Japanese Unexamined Patent Application, Publication No. 2001-215689; PCT International Publication No. WO 2011/007780; Japanese Unexamined Patent Application, Publication Nos. 2009-199021, 2006-321770, 2011-141494, and 2011-141495).
Under such circumstances, in these days when further miniaturization of resist patterns is advancing, it is also demanded to further improve the resolving ability, the LWR performance, and the like, and to increase a depth of focus for the purpose of improving process stability. In addition, in the case of the aforementioned conventional acid diffusion control agents, since the resist pattern formed tends to exhibit a top loss phenomenon and the like, an improvement of the cross-sectional shape of the resist pattern is also demanded. However, the aforementioned conventional photoresist compositions are incapable of meeting these demands.